Method of manufacturing tubular composite metal bodies



p E. MEIER, JR 2,297,491

METHOD OF MANUFACTURING TUBULAR COMPOSITE METAL BODIES Filed Sept. 11,1940 A TTORNEVY Patented Sept. 29, 1942 METHOD or MANUFACTURING TUBULARCOMPOSITE METAL BODIES Ernst Meier, Jr., Brunswick, Germany; vested inthe Alien Property Custodian Application September 11, 1940, Serial No.356,395

In Germany July 4, 1939 4 Claims. (Cl. 22-203) My invention relates toimprovements in the method of manufacturing tubular composite metalbodies, and more particularly in the method in which a tubular body andmore particularly a bearing is made from a main body of cast iron orsteel and a suitable bearing metal such as lead bronze applied thereto.The object of the improvement is to provide a method by means of whichthe said bearing metal is intimately united with the body of steel orcast iron, which is simple in operation, and in which no valuablebearing metal is wasted, and with this object in view my inventionconsists in first melting the said bearing metal at a temperature notmuch higher than the melting point, applying the molten metal to thecold base body of cast iron or steel, and thereafter heating the saidbase body for a short period of time at a temperature higher than themelting temperature of the bearing metal and sufficient to insure aperfect binding by diffusion of the bearing metal to the base body. Ihave found that in this method the surface of the base body to which thebearing metal is applied is not oxidized by the moderately heated moltenbearing metal, so that the metallic surface of the base body ismaintained and no layer of oxidized metal is produced between the basebody and the molten bearing metal.

Further, when subsequently high heat is applied to the base body, thesaid surface of the base body can not be oxidized, because the moltenmetal prevents access of oxygen to the surface of the base body, andtherefore the bearing metal is intimately united by diffusion with thebase body.

Preferably high heat is applied to the base body by means of a highfrequency electric current, or by means of gas burners.

In any case after heating the base body at high temperature it isabruptly cooled or quenched, for example by means of cold water sprayedagainst the body or by immersing the said body into a bath of oil.

An important feature of the method is that the tubular body-of steel oriron is not heated before the molten bearing metal is applied thereto,and therefore a thinlayer of bearing metal is produced thereon which atfirst is not united by diffusion to the base body, and which is rapidlycooled and solidified on the base body which therefore has no time tooxidize.

reference characters have been used in all the views to indicatecorresponding parts. In said drawing Fig. l is an elevation partly insection showing the apparatus used for heating and subsequentlyquenching the tubular body, the tubular body being shown in section, and

Fig. 2 is a perspective sectional view showing one of the members of theapparatus.

For the purpose of explaining the invention it may be assumed that it isdesired to provide a tubular body a of steel with an internal lining cof a suitable bearing metal such as lead bronze. The said composite bodymay be a bearing.

In carrying out the method the inner surface of the body is first freedof any impurity or oxidized coating, and thereafter a thin layer ofbearing metal 0 heated at a temperature not much higher than meltingtemperature is applied to the inner surface of the base body a,preferably by first placing a core b into the body a. It will beunderstood that at the beginning of this operation the base body a is atroom temperature, and that it is not heated before thelining isapplied.v After the lining has thus been applied, the base body and itslining are placed into an apparatus for rapidly heating the base body athigh temperature, and heat isapplied thereto. In the construction shownin Fig. 1, the said apparatus comprises a pair of tongs having a pivotbolt d and adapted to be clamped together at their free ends by means ofa screw and nut 'm. The members of the tongs are formed each with asemi-cylindrical portion f having an inner diameter slightly larger thanthe outer diameter of the base body a so that the For the purpose ofexplaining the invention an I example embodying the same has been shownin base body is embraced by the portions 1 without making contacttherewith and with little clearance. The tongs consist of metal of highconductivity for electricity and heat such as copper, and the members ofthe tongs are metallically connected with each other only through thepivot bolt d while they are insulated from each other at e. To the outerends of the tongs leads g, g are secured which are connected with asource of strong high frequency current, for example to a source of highfrequency alternating current having about 3000 oscillations per second.

The base body a may be held out of contact with the tongs by suitableinsulating material, such as pads of asbestos placed between theportions 1 and the base body a. Preferably the lower member of the tongs,f is fixed to a suitable the accompanying drawing in which the sameIbase while the upper member I may be turned around the pivot 11 andaway from the base body plied for holding the members of the tongstogether. Now the parts are in the positions shown in Fig. 1, in whichthe members I, I are insulated from each other with the exception of theleft hand ends thereof, and in which further, the portions 1 areslightly spaced from the base body (1. Now a strong high frequencyalternating current is applied to the conductors Now the members 7 ofthe tongs act as the coil of an electromagnet, by magnetizing the steelbody a alternately in opposite directions. By the rapid change in themagnetization of the steel body the temperature of the base body a andit lining is increased, within a few seconds, to a temperature higherthan the melting point of the bearing metal 0.

At this high temperature difiusion takes place between the base body aand the bearing metal c, which insures intimate binding of the metals.

When this state is attained the current is interrupted, and the steelbody is rapidly cooled. In the construction shown in the figures coolingis effected by means of jets of water sprayed against the outer surfaceof the base body a and for this purpose the portions ,f are formed withannular chambers n each connected to a supply of cooling water throughflexible tubes h, and the chambers 11 open internally through bores ornozzles i through which jets of cooling water'are thrown vide basebodies a. of the desired length and-ap-' ply thereto the lining c ofbearing metal by means of a suitable core, all the blanks being placedon a conveyer band below a casting apparatus by means of which anexceedingly thin layer of lead bronze is brought into the space betweenthe body a and the core of sand. Thereafter the blanks are passed onthe-conveyor band through a furnace in which the flames of gas burnersare directed to the outside of the body 1 whereby the said base bodiesare heated a short period of time at a temperature higher than themelting temperature of the bearing metal. Thereby the metals of the basebody and the lining diffuse into each other, and the metals areintimately united according to the period of time during which heat isapplied. The gas burners may be disposed within the furnace so that thetreated for completing the bearings.

A bearing made by my improved process may be made with a very thinlining of bearing metal, it has the crystal uniformly distributedtherein for developing the desired qualities in the bearing andtherefore it is particularly suitable for use in air craft.

I claim:

1. A method of making composite tubular bodies, comprising the steps ofmelting metallic material of comparatively low melting point, applyingthe same as a lining to the interior of a metallic tubular member ofrelatively high melting point, which member is at room temperature,thereafter heating the composite body to a temperature above the meltingpoint of the lining material, and thenv rapidly cooling the same,

whereby the lining metal is compressed due to shrinkage of the outertubular member to perfeet the union between the inner and outer layersof the composite body.

2. A method of, making composite tubular bodies comprising the steps ofcleansing the inner surface of a member composed of metal of highmelting point, melting metallic material of comparatively low meltingpoint, applying the same as a lining to the interior of said curvedmetallic member of relatively high melting point, said member being atroom temperature, thereafter heating the composite body so formed to atemperature above the melting point of the lining material, and thenrapidly cooling said body so as to perfect the union of the inner andouter layers of said body due to th compressing ac tion caused byshrinkage of said outer member after solidification of the inner layerof metal.

3. The process of manufacturing unitary laminated tubular bearingscomprising placing a steel tube in a metallic jacket, placing a core inthe tube, pouring molten bearing metal between said tube and core toline the tube while the tube is at room temperature, passing a highfrequency current through said jacket to heat the lined tube rapidly toa temperature above the melting point of the lining thereof, andmaintaining the heat for a suflicient period of time to permit diffusionof the molten metal into the metal of the steel tube.

4. A process as in claim 3, including the step of suddenly chilling thetubular body upon completion of the heating operation.

ms'r MEIER, JR.

